[Bug 1651947] Re: installer ought to install a proper random-seed

Kevin Wall 1651947 at bugs.launchpad.net
Fri Dec 23 22:18:57 UTC 2016 

John,

Just wondering what the Tails Linux distro (https://tails.boum.org/)
does in this regard of initial seeding for /dev/urandom from their
Live CD distro. Do you know? Since it is a LOT more common for
people to run (only?) from the Live distro for Tails, having an
unpredictable PRNG stream would arguably more relevant there.

I don't know what I did with my Tails CD (and plus it's probably
several years old), otherwise I'd fire it up and look. But perhaps if
they did it right, maybe we can just point to them for a better
approach. Alternately, if you know where the Ubuntu Live CD "builder"
script(s) are, maybe the better approach is to just make a Git pull
request and associate it with this bug report. If they had a fix in-hand
or one they could copy from, then I think this would be more likely to
change the importance from "undecided" to at least Low, or maybe
Medium/ (I doubt it will ever be seen more important than that, assuming
they use a H, M, L scale.) It might even get assigned to someone in that
case too.

-kevin

On Fri, Dec 23, 2016 at 2:03 PM, John Denker <lp at av8n.com> wrote:
> I see the importance is still "undecided".  Here is something that may
> help:
>
> Message from Rich Salz, 12/22/2016 10:06 AM:
>> Feel free to quote me:
>>       This is very important.
> [...]
>>  Rich Salz
>>    Senior Architect, Akamai Technologies
>>    Member, OpenSSL Dev Team
>
> High-quality randomly-distributed numbers are needed for every aspect of computer
> security, including long-term keys, session keys, nonces, initialization vectors,
> ASLR, et cetera.
>
> Newly-installed systems need randomness just as much as other systems.
>
> --
> You received this bug notification because you are subscribed to the bug
> report.
> https://bugs.launchpad.net/bugs/1651947
>
> Title:
>   installer ought to install a proper random-seed
>
> Status in livecd-rootfs package in Ubuntu:
>   New
> Status in ubiquity package in Ubuntu:
>   New
>
> Bug description:
>   Observed behavior:  The Ubuntu "Live CD" installer creates
>   a file on the installee (i.e. target) filesystem called
>      /var/lib/systemd/random-seed
>   but alas it has zero length.
>
>   Desired behavior:  The installer should copy 512 bytes from
>   the installer's /dev/urandom into the installee's
>      /var/lib/systemd/random-seed
>
>   Discussion:  The newly installed system relies on that file
>   to initialize its random number generator.  It might have
>   other ways of initializing, or it might not.  An improperly
>   initialized RNG creates grave security problems.
>
>   There is no imaginable downside to doing this.
>
>   Remark:  The Debian installer handles this better.  It gives the
>   installee a nice
>      /var/lib/urandom/random-seed
>   file with 512 bytes of random content.  It does not bother with
>      /var/lib/systemd/random-seed
>   at all.
>
>   The Ubuntu installer, in contrast, creates a directory
>      /var/lib/urandom
>   with no contents, i.e. no files at all.  Perhaps this is vestigial.
>   Suggestion: The Ubuntu installer should:
>     a) not create that directory at all, or
>     b) create /var/lib/urandom/random-seed as a symlink to
>            ../systemd/random-seed, or
>     c) put the actual data in /var/lib/urandom/random-seed --
>      which is the traditional and compatible place for it -- and
>      teach the systemd scripts to find it there.
>
>   Disclaimer:  As a separate matter, it is important to ensure
>   that the installer system itself has a properly initialized RNG.
>   There are ways of doing so, but that is a topic for another day.
>   For present purposes, the point is only that the installer should
>   not make things worse.  It should use whatever randomness it has
>   to initialize the installee system.
>
>   --------------------------------
>
>   Observed on a Live CD system:
>   :; lsb_release -rd
>   Description:    Ubuntu 16.04.1 LTS
>   Release:        16.04
>
>   The package is:
>   :; apt-cache policy ubiquity
>   ubiquity:
>     Installed: 2.21.63.2
>     Candidate: 2.21.63.2
>     Version table:
>    *** 2.21.63.2 500
>           500 http://archive.ubuntu.com/ubuntu xenial-updates/main amd64 Packages
>           100 /var/lib/dpkg/status
>        2.21.63 500
>           500 http://archive.ubuntu.com/ubuntu xenial/main amd64 Packages
>
> To manage notifications about this bug go to:
> https://bugs.launchpad.net/ubuntu/+source/livecd-rootfs/+bug/1651947/+subscriptions


-- 
Blog: http://off-the-wall-security.blogspot.com/    | Twitter: @KevinWWall
NSA: All your crypto bit are belong to us.

-- 
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https://bugs.launchpad.net/bugs/1651947

Title:
  installer ought to install a proper random-seed

Status in livecd-rootfs package in Ubuntu:
  New
Status in ubiquity package in Ubuntu:
  New

Bug description:
  Observed behavior:  The Ubuntu "Live CD" installer creates
  a file on the installee (i.e. target) filesystem called
     /var/lib/systemd/random-seed
  but alas it has zero length.

  Desired behavior:  The installer should copy 512 bytes from
  the installer's /dev/urandom into the installee's 
     /var/lib/systemd/random-seed

  Discussion:  The newly installed system relies on that file
  to initialize its random number generator.  It might have
  other ways of initializing, or it might not.  An improperly
  initialized RNG creates grave security problems.

  There is no imaginable downside to doing this.

  Remark:  The Debian installer handles this better.  It gives the
  installee a nice
     /var/lib/urandom/random-seed
  file with 512 bytes of random content.  It does not bother with
     /var/lib/systemd/random-seed
  at all.

  The Ubuntu installer, in contrast, creates a directory
     /var/lib/urandom
  with no contents, i.e. no files at all.  Perhaps this is vestigial.
  Suggestion: The Ubuntu installer should:
    a) not create that directory at all, or
    b) create /var/lib/urandom/random-seed as a symlink to
           ../systemd/random-seed, or
    c) put the actual data in /var/lib/urandom/random-seed -- 
     which is the traditional and compatible place for it -- and
     teach the systemd scripts to find it there.

  Disclaimer:  As a separate matter, it is important to ensure
  that the installer system itself has a properly initialized RNG.
  There are ways of doing so, but that is a topic for another day.
  For present purposes, the point is only that the installer should
  not make things worse.  It should use whatever randomness it has
  to initialize the installee system.

  --------------------------------

  Observed on a Live CD system:
  :; lsb_release -rd
  Description:    Ubuntu 16.04.1 LTS
  Release:        16.04

  The package is: 
  :; apt-cache policy ubiquity
  ubiquity:
    Installed: 2.21.63.2
    Candidate: 2.21.63.2
    Version table:
   *** 2.21.63.2 500
          500 http://archive.ubuntu.com/ubuntu xenial-updates/main amd64 Packages
          100 /var/lib/dpkg/status
       2.21.63 500
          500 http://archive.ubuntu.com/ubuntu xenial/main amd64 Packages

To manage notifications about this bug go to:
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